MAPPING THE BIODISTRIBUTION AND CATABOLISM OF 5-FLUOROURACIL IN TUMOR-BEARING RATS BY CHEMICAL-SHIFT SELECTIVE F-19 MR-IMAGING

A chemical-shift selective (CHESS) F-19 MR imaging technique was used to map selectively the antineoplastic drug 5-fluorouracil (5-FU) and i ts major catabolite alpha-fluoro-beta-alanine (FBAL) in tumor-bearing rats, The pulse sequence employed a CHESS RF saturation pulse to suppr ess either the 5-FU or the FBAL resonance before the other component i n the two-line F-19 MR spectra was measured, Selective 5-FU and FBAL i mages with a spatial resolution of 10 x 10 x 15 mm(3) (1.5 mi) were ob tained in 40 min from six ACI rats with implanted Morris hepatoma, Bec ause the transmitter frequency could always be set to the Larmor frequ ency of the F-19 resonance employed for imaging, the images were free of chemical-shift artifacts in readout and slice-selection direction, Whereas FBAL appeared only in the liver, the kidneys, and the bladder, 5-FU could also be detected in all major organs and in the muscular s ystem, In the Morris hepatomas, a small 5-FU uptake and no FBAL accumu lation were measured, The CHESS F-19 MRI technique provides useful phy siological and biochemical data on the biodistribution of the antineop lastic drug 5-FU and on the different catabolic activities of the tiss ues.